Grocery Shopping

So, I buy a house in a country that shops everyday – “fare le spezie.” What do I hate to do? Shop for groceries!
There are those Sicilians who still believe that if you buy your necessary items for ‘cena’ (the evening meal) at the same time you are buying your food items for pranzo (lunch), they will not be fresh. On this particular subject, I am American. I have been raised to believe that food bought in the morning on Tuesday, will still be good to eat for lunch on Thursday.
I watch the same thing in Sicily – the produce gets put out in the morning, what doesn’t get sold by lunchtime goes back into the cooler – only to come out again for purchase later in the day.
What’s the difference?